1. Field of the Invention
The invention relates to managed communication networks and more particularly to diagnostic devices for determining the causes of problems occurring in such networks.
2. Description of the Prior Art
The person skilled in the art knows that problems occurring in communication networks can have various causes, for example a power outage, a broken connection, a breakdown or malfunction of a network equipment or a component thereof, software, integrating a version of a network equipment or a component thereof, or software that is not fully compatible with the remainder of the network.
Many diagnostic devices (also known as diagnostic tools) for determining the causes of problems have been proposed in the past. Some use techniques based on object-oriented and/or rules-based programming languages, possibly managed by a rules engine. Of such devices, there may be mentioned, for example, Expert (Event Correlation expert) for constructing alarm correlation trees from rules defined manually, devices from ILOG that use a programmable rules engine for diagnosis, devices from Hewlett Packard, in particular the Network Node Manager®, version 6.4, and the Network Node Manager Extended Topology®, version 2.0, which use a technique based on fault models, the Fault Detective for Data Communications (FDDC) from Agilent, which replaces the fault diagnosis operations effected by technicians with automated diagnostic methods, and the TACO device from CISCO, which is a problem detection assistant.
The main drawback of the above devices is their mode of acquiring information (also referred to as expert knowledge). If the diagnostic device is developed for a company that is not a systems integrator, the knowledge base or expert knowledge base is not well adapted to certain specific equipments or to certain combinations of equipments.
If the diagnostic device is developed by a systems integrator, the knowledge base or expert knowledge base contains only basic information, with the result that certain features specific to the equipment are not taken into account, for example the type, method of fabrication, date of fabrication, version and mode of use. Critical information and the diagnostic devices themselves are generally not communicated to the user client.
Defining new and specific diagnostic or verification technique therefore proves to be very difficult, and sometimes it is even the case that the tool cannot be modified at all. In other words, the above diagnostic devices suffer from a lack of flexibility.
ALCATEL also offers a diagnostic device based on Bayesian probabilistic theory and used to define rules for refining hypotheses on the basis of concepts of additional evidence and background information, which lead to numbers each representing the probability that a hypothesis is true and used to construct Bayesian networks (also known as Bayesian diagrams) defining test operations associated with statistical or probabilistic weights.
The main drawback of the above device is that its Bayesian networks, and the tests associated with them, cannot be modified once they have been integrated. Consequently, if a user client realizes that a Bayesian network is not totally adapted to his network, or that a specific equipment necessitates a particular test, the diagnostic device cannot be adapted. This kind of diagnostic device therefore also suffers from a lack of flexibility.
No prior art diagnostic device proving entirely satisfactory, an object of the invention is therefore to improve on this situation.